I would center it over the carb. First make sure the hood is lined up where you want it and tightened up. If you are going to make it functional get a long piece of threaded rod,turn it into the carb where you have the short one for your air cleaner, bring the hood down so it marks it. Thats where you drill a pilot hole for the larger one you will cut (size up to you but ideally a bit bigger then your air cleaner) .
